Arrangement in a two cycle combustion engine with internal combustion

ABSTRACT

The internal combustion engine has a plurality of cylinders which are arranged in an annular series about a common central drive shaft. Each cylinder includes a pair of opposed pistons which are movable towards and away from each other while defining a combustion chamber therebetween. Each piston is connected to a piston rod which causes rotation of a cam guide device secured to the drive shaft. Each cam guide device has a curved cam surface having portions in phase-displaced relation to the curved cam surface of the other cam guide device as well as portions in mutually-phased relation. The cam surfaces each have a rectilinear portion to define a stationary combustion chamber for combustion between the pistons of each cylinder. The cam guide devices also have portions to permit opening of the exhaust ports prior to opening of the air scavaging ports of the cylinder.

The present invention relates to an arrangement in a two cyclecombustion engine with internal combustion, comprising a plurality ofengine cylinders, which are arranged in an annular series around acommon central drive shaft and which have cylinder axes running parallelto the drive shaft, each cylinder including a pair of pistons movabletowards and away from each other and for each pair of pistons a common,intermediate work chamber, while each piston is equipped with itsaxially movable piston rod, the free outer end of which forms via asupport roller a support against its curve-shaped, that is to say“sine”-like curve shaped, cam guide device, which is arranged at each ofopposite ends of the cylinder and which guides movements of the pistonrelative to the associated cylinder.

Geometric Considerations of the Afore-mentioned Motor System

When the drive shaft of the engine is moved in a circular path, theoscillation movements of the engine pistons can correspondinglyaccording to the afore-mentioned motor system be observed graphically asto time in a sine-shaped curve path according to

Formula 1: y=sine x.

From DE 43 35 515 it is priorly known two stroke engines of the artdescribed initially, having a single cylinder provided with two opposedpistons and having conventional crank shafts and conventional crankarms. Formel 1 is also relating to each crank shaft of such engine. Inorder to optimise the combustion in such engine it is suggested mutuallydisplaced piston movement phases for the two opposed pistons of thecylinder.

By the use of a sine curve-shaped cam guide device and respectively bythe use of conventional crank shafts the backwards and forwards pistonmovements of the individual pistons of the cylinders can in fact becontrolled, so that the oscillation movements of the pistonssynchronously coincide with the rotational movement of the drive shaft.Over the course of a complete rotation of the drive shaft, the pistonsare moved backwards and forwards in a forcibly controlled manner in oneor more working strokes, which are accurately synchronised with therotational movement of the drive shaft. In other words the rotationalmovement of the cam guide device and the drive shaft will be directlyconnected to the oscillation movement of the pistons, and vice-versa.

The backwards and forwards movements of the pistons will correspondinglyconstitute a multiple of the rotary movement of the drive shaft witheach 360° rotation of the drive shaft. In other words each piston willmove backwards and forwards in the associated cylinder a total number oftimes, that is to say from one to for example four times with each 360°rotation of the drive shaft.

Owing to the cam guide device, which controls the oscillating movementsof the pistons in an associated cylinder, being rotated synchronouslywith the drive shaft of the engine, the oscillation movements of thepistons can consequently be controlled by designing the cam guide devicewith a sine-shaped curve contour, so that these conform to therotational movement of the drive shaft.

“Sine”-like Concept.

When the term “sine”-like is employed herein in connection withexpressions, such as “sine”-like concept, “sine”-like curve, “sine”-likeplane, etc.), a curve contour is expressed which does not constitute amathematical sine contour according to the formula 1 above, but on theother hand expresses a varying curve contour, which only generallyresembles the path of a mathematical sine contour. By the term“sine”-like contour there shall be designated generally herein a contourwhich is like but differs from a sine contour.

According to the invention the aim is, in certain constructionalconnections, with regard to designing the cam guide device with aparticular curve contour which in different ways deviates from amathematical sine contour.

Generally this means further, according to the invention, that bydesigning the cam guide device with a specially fashioned “sine”-likecontour, which deviates from a conventionally known sine contour, thepiston movements can be adapted in a corresponding manner to additionalengine functions relative to the rotational movement of the drive shaftand relative to previously proposed solutions.

According to the invention the general aim is to design the cam guidedevice so that there is a possibility of achieving optimum operatingconditions for pistons of the motor, based on a simple and operativelyreliable operating sequence.

When one speaks herein about “sine”-like plane, there is meant the localpart of the cam guide device, which has a “sine”-like curve contour. Inpractice the individual cam guide device has a 360° arcuate contour,which corresponds to a multiple of such said “sine”-like planes.

Combustion engines, where the axial movement of the pistons isindividually controlled by a cam guide device via associated “sine”-likeplanes, function generally according to the so-called “sine”-likeconcept, which has been known for a number of years.

Originally the “sine”-like plane has had a contour, which resembles to alarge degree the mathematical sine contour, that is to say with mutuallysymmetrical and uniformly curved curve portions.

According to the patent literature, curve contours have gradually beenproposed which in different ways deviate from the mathematical sinecontour. This is also typical of the curve-contour of the cam guidedevices according to the present invention.

According to the “sine”-like concept the mechanical energy istransferred from the single piston to the common drive shaft of theengine cylinder, that is to say via a support roller of an associatedpiston rod to the “sine”-like plane of the cam guide device. The“sine”-like planes, which separately control the oscillation movementsof the pistons, transfer during the oscillation movements of thepistons:

partly kinetic energy from the expansion stroke of the pistons via the“sine”-like plane to the drive shaft, so as to subject the drive shaftto a rotary movement with associated torque, and

partly torsional moments from the drive shaft via the “sine”-like planeback to the pistons, so as to subject the pistons to the necessarykinetic energy during the compression stroke.

In combustion engines of the kind indicated by way of introduction thepistons are moved axially backwards and forwards in associatedcylinders, almost exclusively in rectilinear movements axially along thedrive shaft, while the piston rods and associated support rollers aremoved in corresponding rectilinear movements and consequently transfermotive forces from the support rollers to the associated “sine”-likeplane in an axial direction along the drive shaft.

The transfer of the motive forces from the pistons via support rollersto the “sine”-like plane, which is designed in driving connection withthe drive shaft, and return forces which are transferred in the oppositedirection from the drive shaft to the pistons via the “sine”-like plane,occur on curve portions which extend obliquely of the rotational planeof the drive shaft. In other words motive forces are transferred betweenthe support rollers and the “sine”-like plane during displacement of thesupport rollers axially along the drive shaft. In the dead pointsbetween the backwards and forwards going piston stroke there occurshowever no transfer of motive forces, this despite that in the one deadpoint, that is to say at the close of the compression stroke and afterignition of injected fuel, significant motive forces arise between thepistons going towards and away from each other.

With the present invention the particular aim is to utilize thelast-mentioned condition in connection with a special design of the camguide device, so that in said dead point a hitherto disregardedpossibility can be achieved for controlling the combustion process ofthe engine in an especially favorable manner.

Comparison of Four Stroke and Two Stroke Engines.

In a four stroke combustion engine the piston rods transfer their motiveforces via the “sine”-like plane in the respective four strokes, that isto say

with minimal forces in the air suction stroke,

with substantially greater forces in the compression stroke,

with the largest forces in the expansion stroke and

with minimal forces in the exhaust ejection stroke.

In a two stroke-combustion engine the piston rods transfer their motiveforces via the “sine”-like plane in the respective two strokes, that isto say

with relatively small forces in a combined air injection and compressionstroke and

with substantially greater forces in a combined expansion and exhaustejection stroke.

However it is also usual to allow air suction/air injection and exhaustejection to occur more or less in parallel at the end of the combinedexpansion and exhaust ejection stroke and at the beginning of thecombined air injection and compression stroke.

Four stroke engines have hitherto generally had a dominating use on themarket, relative to the two stroke engine, within many different fieldsof application (by way of example for petrol engines for private cars).As a result of the operating strokes of the four stroke motor beingdistributed over four piston strokes, there is a greater prospect ofadapting the individual functions of the single strokes in a simplermanner than in a two stroke engine, where all the current functions mustbe adapted over two strokes.

The functions of the two stroke engine are necessarily more compact andthereby also more complicated, than in four stroke engines. Four strokeengines have hitherto also been simpler to adapt with the “sine”-likeconcept than two stroke engines. On the other hand two stroke engineshave various other advantages over four stroke engines, precisely as aconsequence of a fewer number of operating strokes.

With the present invention the aim is inter alia to solve the problemsone has hitherto had with two stroke engines in connection with theapplication of the “sine”-like concept. According to the invention theaim is to design the cam guide device in a particular manner, so thatthe “sine”-like concept can be utilized in two stroke engines undercorrespondingly favorable or under still better operating conditionsthan in four stroke engines.

Historic Development of the “sine”-like Concept:

A four stroke combustion engine is known from for example U.S. Pat. No.1,352,985 (1918) having a single cam guide device. The cam guide deviceis based on a sole, common cam control for a sole, annular series ofpistons in each of their associated separate engine cylinders. Each andall the cylinders are correspondingly arranged in a sole, annular seriesaround the drive shaft of the engine. The piston rods are separatelyshored up via their respective support rolls in the common cam guidedevice.

From U.S. Pat. No. 1,802,902 (1929) for instance a four strokecombustion engine is known having a corresponding single cam guidedevice. In this case, instead of just one series of pistons, there areemployed two series of pistons axially separated, but mutually directlycoupled together. The pistons are arranged in tandem in their respectiveaxially oppositely facing cylinders, that is to say the cylinders andthe pistons are placed aligned in pairs, axially opposite each other.The pistons are furthermore rigidly connected to each other via a commonpiston rod and have their respective piston heads turned away from eachother at axially opposite ends of the engine each towards its respectiveworking chamber in its respective associated cylinder. The pistonscooperate in pairs with just one, common cam guide device. The commonpiston rod of each pair of pistons is provided in a middle regionbetween the shirt portions of the pistons with a common support roller,which is supported and is controlled in a common, sole cam guide devicefor all the pistons. More specifically a centrally arranged cam guidedevice is employed with a double-sided arrangement of mutually opposite“sine”-like planes following in series, which cooperate with a singleseries of support rollers.

The aforementioned placing of the cam guide device and the supportrollers centrally between two series of mutually opposite pistons, wherethere is employed a single series of support rollers in a common,double-sided cam guide device, gives little possibility of deviatingcontours in the two co-operating series of oppositely facing “sine”-likeplanes, since the contours of the “sine”-like planes are necessarilyadapted after the opposite working phase of the respective twooppositely facing pistons of the pair of pistons.

From U.S. Pat. No. 5,031,581 (1989) for instance a four strokecombustion engine is known having two separate cam guide devices. Inaddition said patent is relating to a two stroke engine. Each cam guidedevice, which co-operates with its respective set of pistons and withits respective associated set of support rollers, is individuallydesigned corresponding to the construction according to U.S. Pat. No.1,352,985.

According to U.S. Pat. No. 5,031,581 the cylinders are arranged in asingle group of cylinders, that is to say the cylinders are arranged inan annular single series around the drive shaft. The pistons, which arereceived in pairs in a respective one of the cylinders, are served bytwo separate cam guide devices, that is to say the one piston of eachpair of pistons is controlled by a first cam guide device, while theremaining piston is controlled by a second cam guide device. Eachcylinder is consequently equipped with separate pistons movable in pairstowards and away from each other each with its separate piston rod,which co-operates individually via an associated support roller with arespective one of two opposite cam guide devices with associated“sine”-like planes. The cam guide devices of the two axially distinctgroups of pistons are arranged axially endwise outside respective endsof the engine. The piston heads of said pairs of pistons face mutuallytowards each other in a common working chamber of the associatedcylinder, that is to say towards a common working chamber, which isarranged midway between said pair of pistons.

In GB 2 019 487 a four cylinder two stroke engine is shown with a pairof pistons going towards and away from each other in each of said fourcylinders. An arrangement is employed where the ignition occurssimultaneously in two of the four cylinders, that is to say in pairs ofalternate cylinders. In the patent specification it is indicated thatthe contour of the cam can be designed so that the pistons can be movedin a most favorable manner in connection with expansion of thecombustion product. There is employed a desired level or steady contourfor emptying or scavenging of exhaust before new fuel is introduced intothe cylinder. In the drawings there is shown, in each of two mutuallyopposite cam grooves, a more or less rectilinear, local cam contour inmutual turning points lying directly opposite each other forming“sine”-like curve portions. More specifically the rectilinear camcontour is illustrated in only the one of two succeeding, turning pointsof the “sine”-like curve forming “sine”-like curve portions, namelywhere the respective pistons occupy one after the other their mostremote outer positions with exhaust and scavenging ports open to themaximum.

Present Invention.

The present invention, which relates to two cycle engines, takes itsstarting point as to arrangement in a four cycle engine with piston andcylinder arrangement according to the afore-mentioned U.S. Pat. No.5,031,581. In particular the aim according to the invention is to beable to adapt the “sine”-like concept to a two stroke engine, so that atleast equally favorable and preferably still more favorable operatingconditions can be achieved than what are attained in the four stroke (ortwo stroke) engine according to U.S. Pat. No. 5,031,581.

In a four cycle engine four respective strokes (air injection stroke,compression stroke, expansion stroke and exhaust rejection stroke) areemployed one after the other, so that the different engine functions canbe accommodated in each stroke, while in a two cycle engine the exhaustrejection and air injection take place in the transition zone betweenthe expansion stroke and the compression stroke, that is to say indirect connection with remaining engine functions in each workingsequence. With a two cycle engine different functions of the twooppositely directed cycles must consequently be combined.

According to the present invention the aim is also to combine thevarious engine functions in a two cycle engine in an especiallyfavorable manner, in a particular design of the “sine”-like plane of thepistons, such as will be described in more detail below.

Inter alia the aim is, correspondingly as shown in a two cycle engineaccording to GB 2 019 487, to employ a more or less rectilinear contourin the turning point-forming “sine”-like curve portions where thepistons assume their most remote outer position with exhaust andscavenging ports open to the maximum.

According to the invention is employed the following combination:

that the “sine”-like plane does not need to have a curve contour, whichlies as closely or tightest possible up to, but on the contrary candepart to a significant degree from a “sine”-like contour and frompreviously known “sine”-like contours, and

that the cam guide devices can be designed with “sine”-like planes,which can vary to a significant degree mutually from each other, whilein addition an especially favorable engine solution can be achievedtotally.

The arrangement according to the invention is characterized in that thetwo pistons in each cylinder have mutually differing piston phases,which are controlled by mutually differing cam guide devices, the camdevices being designed with equivalent mutually differing “sine”-likeplanes, the respective cam guide devices of the two pistons arephase-displaced relative to each other in certain portions of the“sine”-like planes and in remaining portions of the “sine”-like planesare in mutual phase.

According to the invention there can be achieved an especially favorablecontrol and thereby favorable accommodation of the different workingfunctions in a two cycle engine.

Especially, it is made possible to accommodate the working functions atthe top and/or bottom of the “sine”-curve in mutually different ways,whereas the respective intermediate “sine”-like curve portions can bearranged in common or more or less common manner.

Thereby on can ensure according to the invention movement of the pistonsof the pair of pistons in a mutually differing manner, but neverthelessachieve favorable collective working conditions in a common workingchamber between piston heads of the pair of pistons.

Phase Displacement of the Cam Guide Devices.

A practical, especially favorable solution according to the invention isachieved in that the respective cam guide devices of the two pistons,are phase-displaced relative to each other, in certain portions of the“sine”-like plane.

This means firstly, according to a first aspect of the presentinvention, an opportunity to extend the combustion phase in relation tothe following compression phase respectively in relation to thepreceding expansion phase by phase displacement of the “sine”-like curvetops.

According to a second aspect of the present invention a favorable,separate control of the scavenging air ports can be obtained via the camguide device of the one piston and a correspondingly favorable, separatecontrol of the exhaust ports via the cam guide device of the otherpiston. Consequently, by such phase displacement, the opening andclosing of the scavenger ports and the exhaust ports at various pointsin time can be achieved and these points in time can be determined byequivalent designing of the individual cam guide device.

Stated in another manner the two pistons can separately open and closeassociated ports (exhaust ports/scavenger air ports), while therespective piston occupies a corresponding axial position in theassociated cylinder, but by virtue of the mutual phase displacementbetween the piston movements, the opening and closing of the variousports can take place correspondingly phase-displaced.

Special Design of the “sine”-like Plane.

By designing a “sine”-like plane portion rectilinearly or largelyrectilinearly in a plane at right angles to the driving axis of theengine, a hitherto disregarded possibility is obtained for creatingespecially favorable working conditions during the combustion phase ofthe fuel. According to the invention it will in fact be possible todefine in the working chamber a particular combustion chambercorresponding to said working chamber portion by means of a particulardesign of the “sine”-like plane. This combustion chamber canconsequently have a constant or approximately constant volume over arelatively large arcuate length of the longitudinal dimension of the“sine”-like plane and of the rotational arc of the drive shaft, so thatlarge portions, for instance the whole or largely the whole of thecombustion process can take place in said combustion chamber.

When it is indicated herein that the combustion chamber can have aconstant or largely constant volume this has a connection with thedetailed design of the “sine”-like plane at the dead point between thecompression stroke and the expansion stroke.

In other words with an accurate rectilinear portion in the “sine”-likeplane corresponding constant volumes can be obtained, while with a moreor less rectilinear portion equivalent largely constant volumes can beobtained. This involves being able to adapt the contour of the“sine”-like plane according to practical conditions in different casesof application.

In practice partly rectilinear “sine”-like plane portions and partlypreceding and subsequent, largely rectilinear “sine”-like plane portionscan be employed.

By the afore-mentioned solution, which is based on a combustion chamberwith a constant or largely constant volume in a dead portion at thetransition from compression stroke to expansion stroke, one has firstlya chance of utilizing the energy collected which is generated in thecombustion process and having full power even at the beginning of theexpansion phase. Consequently said energy can be utilized with fulleffect immediately the respective piston has moved itself past its deadpoint or its dead portion. This discharge of energy can thereby be usedat full strength already in said curved transition portion where thepiston accelerates from the stationary to optimal piston movement andcan thereafter continue at great strength in the following expansionphase.

Secondly, with such a combustion chamber having constant volume, one hasthe possibility of obtaining a more favorable combustion of the fuel,that is to say combustion of larger portions of the fuel, even beforethe expansion phase starts. This can be ensured by providing thatconsiderable portions of the fuel are consumed in the combustion chamberin or just at said dead portion.

In addition a better utilisation of the energy of the fuel is obtainedviewed totally, by being able to ensure that a higher portion of thefuel by way of percentage is consumed in the working chamber beforeexhaust gases are discharged from the working chamber at the close ofthe expansion stroke.

In other words there is the possibility according to the invention ofincreasing the output of the engine to a significant degree relative topreviously known solutions.

According to the invention there is consequently obtained a generallygreater engine output. In addition the escape of CO gas, NOX gas, andthe like is reduced, and thereby a better environmental combustion isalso obtained.

There must also be mentioned that after-combustion of the fuel, whichoccurs in the expansion stroke per se and which to a large degree cancompensate for the volume enlargement in that portion of the workingchamber where oscillation movements of the pistons take place, can becarried out according to the invention in a controlled manner in goodtime before the exhaust ports open, that is to say gradually as theexpansion stroke propagates itself in the working chamber.

In other words one has a chance to distribute the motive power in anadvantageous manner from the beginning of the expansion stroke andfurther through considerable portions of the expansion stroke before theexhaust ports open, even with an optimal combustion already before theexpansion stroke.

The energy which is discharged, by the released possibility of movementof the pistons from the stationary condition, can consequently bedischarged relatively momentarily and at full strength from a combustionchamber having a constant volume. The discharge itself can occur in anaccelerating manner via a curved “sine”-like plane portion, whichconstitutes the transition portion between said rectilinear dead portionand a subsequent rectilinear expansion portion. In the subsequentrectilinear expansion portion, the expansion takes place linearly, thatis to say in a working chamber having roughly speaking a linearincreasing volume.

ILLUSTRATION BY DRAWINGS

Further features of the present invention will be evident from thefollowing description having regard to the accompanying drawings, whichshow some practical embodiments and in which:

FIG. 1 shows a vertical section of an engine according to the invention.

FIGS. 1a and 1 b show in a corresponding segment of FIG. 1 vital partsof the engine and illustrate in FIG. 1a pistons of the engine in aposition with maximum mutual spacing and in FIG. 1b pistons of theengine in a position with minimal mutual spacing.

FIG. 2 shows schematically a first cross-section illustrated at one endof the cylinder of the engine in which there is shown a scavenging airintake.

FIG. 3 shows schematically a second cross-section illustrated at theother end of the cylinder of the engine, in which there is shown anexhaust outlet.

FIG. 4a shows schematically in a third cross-section, the middle portionof the engine cylinder, where the fuel is supplied and the ignition ofthe fuel occurs, illustrated in a first embodiment.

FIG. 4b shows in a cross-section, which corresponds to FIG. 4a, themiddle portion of the cylinder according to a second embodiment.

FIG. 5a shows in longitudinal section a segment of the engine accordingto FIG. 1b.

FIG. 5b shows a cam guide device with associated drive shaft,illustrated in longitudinal section with a segment of the engineaccording to FIG. 1b.

FIG. 5c shows a cross head in side view.

FIGS. 5d and 5 e show the cross head according to FIG. 5c seenrespectively from above and below.

FIG. 5f shows the piston rod seen in side view.

FIG. 5g shows the piston rod according to FIG. 5f seen from above.

FIG. 5h shows a piston according to the invention in vertical section.

FIGS. 6-8 show schematically illustrated and spread in the plane of thedrawing a general pattern of movement for a first of two pistonsassociated with each cylinder, used in connection with a three cylinderengine, and illustrated in different angular positions relative to therotary movement of the drive shaft.

FIG. 6a shows schematically the principle for transferring motive forcesbetween the roller of the piston rod and an associated obliquelyextending portion of a “sine”-like plane.

FIG. 9 shows schematically illustrated and spread in the plane of thedrawing a more detailed pattern of movement for two pistons of eachcylinder, illustrated in different angular positions relative to therotary movement of the drive shaft, illustrated in connection with afive cylinder engine.

FIG. 10 shows in a representation corresponding to FIG. 9, the pistonsin respective positions relative to associated cylinders, in asubsequent working position.

FIG. 11 shows schematically a segment of a central portion of a“sine”-like plan for two associated pistons of each cylinder.

FIG. 12 shows a detailed curve contour for a “sine”-like plane for afirst piston in each cylinder.

FIG. 13 shows a corresponding detailed curve contour for a “sine”-likeplan for a second piston in each cylinder.

FIG. 14 shows a comparative compilation of the curve contours accordingto FIGS. 12 and 13.

FIG. 15 shows in section and in longitudinal section an alternativeconstruction of a cam guide device with associated pressure rollersarranged at the outer end of a piston rod.

FIG. 16 shows the same alternative solution, as illustrated in FIG. 15,shown in section in a direction radially outwards from the cam guidedevice.

FIGS. 17 and 18 show in elevation and in horizontal section respectivelythe guiding of the head portion of the piston rod along a pair ofcontrol bars extending mutually in parallel.

In connection with FIG. 1 reference herein shall generally be made to atwo cycle combustion engine 10 having internal combustion. Especiallythere will be described such an engine 10 adapted according to aso-called “sine”-like concept. In FIG. 1 there is specifically shown acombustion engine 10 according to the invention illustrated incross-section and in a schematic manner.

According to the invention the aim according to a first aspect of theinvention is combustion in a specially defined combustion chamber K1(see FIG. 1b), as will be described in more detail below.

Furthermore according to a second aspect according to the invention theaim is a favorable control of opening and closing exhaust ports 25 andscavenging ports 24, as will be described further below.

In the embodiment illustrated in FIG. 1 there is shown a drive shaft 11in the form of a pipe stump, which passes axially and centrally throughthe engine 10.

The drive shaft 11 is provided at its illustrated one end with aradially outwardly projecting, first head portion 12 a, which forms afirst cam guide device. at its other illustrated end the drive shaft 11is provided with an equivalent radially outwardly projecting, secondhead portion 12 b, which forms a second cam guide device.

The head portions/the cam guide devices 12 a,12 b in the illustratedembodiment are represented separately and are connected separately tothe drive shaft 11 each with their fastening means.

The cam guide device 12 a surrounds the drive shaft 11 at its one end 11a and forms an end support against end surface 11 b of the drive shaft11 via a fastening flange 12 a′ and is stationarily secured to the driveshaft via fastening screws 12 a″.

The cam guide device 12 b surrounds a thickened portion 11 c of thedrive shaft 11 at its opposite end portion 11 d. The cam guide device 12b is not, as is the cam guide device 12 a directly secured to the driveshaft 11, but is on the other hand arranged axially displaceable alimited extent axially along the drive shaft 11, especially with theidea of being able to regulate the compression ratio in cylinders 21 ofthe engine 10 (only the one of a number of cylinders is shown in FIG.1).

End portion 11 d (see FIGS. 1 and 5a) of the drive shaft 11 forms aradially offset sleeve portion to which there is fastened cup-shapedcarrying member 13. The carrying member 13 is provided with a fasteningflange 13′ which with fastening screws 13″ is secured to end portion 11d of the drive shaft 11. Between upper end surface 13 a of the carryingmember 13 and an opposite shoulder surface 11 e of the drive shaft 11there is defined a pressure oil chamber 13 b. In the pressure oilchamber 13 b there is slidably received a compression simulator 12 b′ inthe form of a piston-forming guide flange, which projects from the innerside of the cam guide device radially inwards into the pressure oilchamber 13 b for sliding abutment against the outer surface of the endportion 11 d.

In order to prevent mutual turning between the cam guide device 12 b andthe carrying member 13 and the drive shaft 11 the guide flange 12 b′ ispassed through by a series of guide pins 12′ which are anchored in theirrespective bores in the end surface 13 a of the carrying member 13 andin the shoulder surface 11 e of the drive shaft 11.

The pressure oil chamber 13 b is supplied pressure oil and is drained ofpressure oil via transverse ducts 11 f and 11 g through end portion 11 dof the drive shaft 11.

An oil guide means 14, which is put axially inwards into mutuallyaligned axial bores in the end portion 11 d of the drive shaft 11 and infastening flange 13′ of the carrying member 13, provides for pressureoil and return oil to be led to and from the ducts 11 f and 11 g viaseparate guide ducts 14 a and 14 b and adjacent annular grooves 14 a′and 14 b′ in the oil guide means 14.

Control of pressure oil and return oil to an from the pressure oilchamber 13 b on opposite sides of the compression simulator 12 b′ of thecam guide device 12 b takes place from a remotely disposed commerciallyconventional control arrangement, not shown further, in a manner notshown further.

The drive shaft 11 is, as shown in FIG. 1, connected at opposite ends toequivalent drive shaft sleeves 15 a and 15 b. The sleeve 15 a isfastened with fastening screws 15 a′ to the cam guide device 12 a, whilethe sleeve 15 b is fastened with fastening screws 15 b′ to the carryingmember 13. The sleeves 15 a and 15 b are rotatably mounted in arespective one of two opposite main support bearings 16 a,16 b, whichare fastened at opposite ends of the engine 10 in a respective end cover17 a and 17 b.

As shown in FIG. 1, the end covers 17 a and 17 b are correspondinglyfastened to an intermediate engine block 17 by means of fastening screws17′.

Internally in the engine 10 a first lubricating oil chamber 17 c isdefined between the end cover 17 a and the engine block 17 and a secondlubricating oil chamber 17 d between the end cover 17 b and the engineblock 17. There is shown an extra cap 17 e attached to the end cover 17b and an external oil conduit 17 f between the lubricating oil chamber17 c and the oil cap 17 e. Further there is illustrated a suctionstrainer 17 g connected to a lubricating oil conduit 17 h which forms acommunication between the lubricating oil chamber 17 d and an externallubricating oil arrangement (not shown further).

The oil guide means 14 is provided with a cover-forming head portion 14c which is fastened to end cover 17 b of the engine 10 with fasteningscrews 14 c′. The cover-forming head portion 14 c forms a sealing offrelative to the lubricating oil chamber 17 c endwise outside the supportbearing 16 b. Correspondingly there is fastened to the end cover 17 aendwise outside the support bearing 16 a a sealing cover 14 d withassociated sealing ring 14 e.

The engine 10 is consequently generally constructed of a drivencomponent, that is to say a rotatable component, and a drivingcomponent, that is to say a non-rotating component. The driven componentcomprises drive shaft 11 of the engine and carrying member 13 of thedrive shaft and drive shaft sleeves 15 a,15 b plus the cam guide devices12 a and 12 b, which are connected to the drive shaft 11. The driving,non-rotating component comprises cylinders 21 of the engine withassociated pistons 44,45.

According to the present invention there is ensured a regulation of thecompression ratio of the engine by effecting a regulation internally,that is to say mutually between the parts of the driven component. Morespecifically the one cam guide device 12 b is displaced axiallybackwards and forwards relative to the drive shaft 11, that is to saywithin the defined movement space in said pressure oil chamber 13 a,which is determined by the guide flange 12 b′ and the part-chambers ofthe oil chamber 13 a on opposite sides of the guide flange 12 b′.

In practice it is a question of a regulation length of some fewmillimeters for smaller motors and of some centimeters for largerengines. The respective volume differences of the associated workingchambers have however equivalent compression effects in the differentengines.

For instance a stepwise or stepless regulation of the compression ratioscan be considered according to need, for example adapted with graduatedcontrol of the cam guide device 12 b to respective positions relative tothe drive shaft 11. The control can for example occur automatically bymeans of electronics known per se, based on different temperaturesensing equipment, and the like. Alternatively the control can occur bymanual control via suitable regulation means, which are not shownfurther herein.

By effecting the regulation of the cam guide device 12 b in connectionwith the driven component of the engine, one avoids influence on thegeneral control of the arrangement of associated piston 44, piston rod48, main support wheel 53 and auxiliary wheel 55, that is to sayinfluence on the mechanical connection between the driving component andthe driven component is avoided.

On the other hand, with such a regulation of the cam guide device 12 b,there is obtained an axial regulation internally in the drivingcomponent, in such a way that the arrangement of piston 44, piston rod48, main support wheel 53 and auxiliary wheel 55 can be displacedcollectively via the cam guide device 12 b relative to the associatedcylinder 21, independently of the concrete compression regulation inpractice.

In FIGS. 1 and 1b there is indicated by a broken line a centre space 44′between the piston heads of the pistons 44,45 at a normal compressionratio when the cam guide device 12 b occupies the position illustratedin FIG. 1. By the full line there is indicated a centre space 44″between the piston heads of the pistons 44,45 when guide flange 12 b′ ofthe cam guide device 12 b is pushed to the maximum upwardly against theshoulder surface 11 e of the piston rod 11.

The engine 10 is shown divided up into three stationary main components,that is to say a middle member, which constitutes the engine block 17and two cover-forming housing members 17 a,17 b which are arranged at arespective one of the ends of the engine 10. The housing members 17 b,17 c are consequently adapted to cover their respective cam guidedevices 12 a,12 b, support wheels 53 and 55 and their associatedbearings in respective piston rods 48,49 at their respective end of theengine block 17. All the driving and driven components of the engine areconsequently effectively enclosed in the engine 10 and received in anoil bath in the associated lubricating oil chambers 17 c and 17 d.

In the engine block 17 in the illustrated embodiment, there is used inconnection with a three cylinder engine, correspondingly designed withthree peripherally separated engine cylinders 21. Only the one of thethree cylinders 21 is shown in FIGS. 1, 1 a and 1 b.

The three cylinders 21, which are placed around the drive shaft 11 witha mutual angular spacing of 120°, are designed according to theillustrated embodiment as separate cylinder-forming insert members,which are pushed into an associated bore in the engine block 17.

In each cylinder/cylinder member 21 there is inserted a sleeve-shapedcylinder bushing 23. In the bushing 23 there is designed, as shownfurther in FIGS. 1a and 1 b (see also FIGS. 2 and 3), an annular seriesof scavenging ports 24 at one end of the bushing 23 and an annularseries of exhaust ports 25 at the other end of the bushing 23.

Equivalently in wall 21 a of the cylinder 21 there are arrangedscavenging ports 26, which are radially aligned with scavenging ports 24of the bushing 23, as is shown in FIG. 2, while exhaust ports 27, whichare radially aligned with exhaust ports 25 of the bushing 23, areequivalently designed in the cylinder wall 21 a, as is shown in FIG. 3.

In FIG. 1 there is shown an annular inlet duct 28 for scavenging air,which surrounds the scavenging ports 26, and a scavenging air intake 29lying radially outside.

As is shown in FIG. 2 the scavenging air ducts 28 extend at asignificant oblique angle u relative to a radial plane A through thecylinder axis, specially adapted to put the scavenging air in arotational path 38 internally in the cylinder 21, as is shown by anarrow B in FIG. 2.

There is further shown in FIG. 1 an annular exhaust outlet duct 30,which surrounds the exhaust ports 27, plus an exhaust outlet 31 emptyingradially outwards.

In FIG. 3 there is shown an equivalent oblique run of the exhaust ports27 at an angle v relative to the radial plane A through the cylinderaxis, specially adapted to lead the exhaust gases from the rotationalpath 38 internally in the cylinder in an equivalent rotational pathoutwards from the cylinder 21, as is shown by an arrow C. The exhaustports 27 are shown opening radially outwards to facilitate the outwardflow of the exhaust gas from the cylinder 21 outwards towards theexhaust outlet duct 30.

In the conventionally known manner the scavenging air is used to pushout exhaust gas from a preceding combustion phase in the cylinder, inaddition to supplying fresh air for a subsequent combustion process inthe cylinder. In this connection there is employed according to theinvention in a manner known per se a rotating air mass as shown byarrows 38 (see FIGS. 1a and 4 a) in working chamber K of the cylinder 21in the compression stroke.

In FIGS. 1a,1 b and 4 a there is shown a fuel injector or nozzle 32received in a cavity 33 in the cylinder wall 21 a. The injector/nozzle32 has a pointed end 32′ (see FIG. 4a) projecting through a bore 34 inthe cylinder wall 21 a. The bore 34 passes through the cylinder wall 21a at an oblique angle, which is not marked further in FIG. 4a, but whichcorresponds to the angle u, as shown in FIG. 2. The pointed end 32′projects further through a bore 35 in the bushing 23, in alignment withthe bore 34. Mouth 36 (see FIG. 4a) of the nozzle/injector 32 isarranged so that a jet 37 of fuel can be directed, as is shown in FIG.4a, obliquely inwards in a rotating mass of air as shown by the arrows38 in cylinder 21, just in front of a spark plug 39 (possibly ignitionpin) arranged in a chamber zone which forms a part of the combustionchamber K1 (see FIG. 1b).

In FIG. 4b there is shown an alternative construction of the solution asshown in FIG. 4a, there being employed in addition to a first fuelnozzle 32 and a first ignition arrangement 39 a second fuel nozzle 32 aand a second ignition arrangement 39 a in one and the same disc-formedcombustion chamber K1. Both the nozzles 32 and 32 a are designedcorrespondingly as described with reference to FIG. 4a and both theignition arrangements 39 and 39 a are corresponding as described withreference to FIG. 4a. In the nozzle 32 a the associated components aredesignated with the reference designation “a” in addition.

In the illustrated embodiment of FIG. 4b the nozzles 32,32 a are shownmutually displaced an angular arc of 180°, while the ignitionarrangements 39,39 a are correspondingly shown mutually displaced anangular arc of 180°. In practice the relative spacings can be altered asrequired, that is to say with different mutual spacings, for instancedepending upon the point in time of the mutual ignition, and the like.

Further there is indicated in FIG. 1 a cooling water system for generalcooling of the cylinder 21. The cooling water system comprises a coolingwater intake not shown further having a first annular cooling water duct41 and a second annular cooling water duct 42. The ducts 41,42 aremutually connected via an annular series of axially extending connectingducts 43 (see FIG. 3). The axially extending ducts 43 pass through thecylinder wall 21 a in each intermediate zone 27 a between the exhaustports 27, so that these zones 27 a especially can be prevented fromsuperheating by being subjected locally to a flowing through of coolingmedium. The discharge of cooling water, which is not shown further inFIG. 1, is connected to the cooling water duct 42 remote from thecooling water intake, in a manner not shown further.

Internally in the bushing 23 there are two axially movable pistons 44,45movable towards and away from each other. Just by the respective top 44a,45 a of the piston and by the skirt edge 44 b,45 b of the piston thereis arranged a set of piston fourths 46 in a manner known per se. Thepistons 44,45 are movable synchronously towards and away from each otherin a two cycle engine system.

Further details of the pistons are shown in FIG. 5h. The piston 44 isshown in the form of a relatively thin-walled cap having top portion 44a and skirt portion 44 b. Innermost in the internal hollow space of thepiston there is arranged a support disc 44 c, thereafter follows a headmember 48 c for an associated piston rod 48, a support ring 44 d and aclamping ring 44 e.

The head member 48 c is provided with a convexly rounded top surface 48c′ and concavely rounded off bottom surface 48 c″, while the supportdisc 44 c is designed with an equivalent concavely rounded upper supportsurface 44 c′ and the support ring 44 d is provided with a convexlyrounded lower support surface 44 d′. The head member 48 c isconsequently adapted to be tilted about a theoretical axis relative tothe piston controlled by the support surfaces 44 c′ and 44 d′. Byabutment against a shoulder portion 44 f internally in the piston thering 44 e provides for the head member 48 c—and thereby the piston rod48—having a certain degree of fit and thereby a certain possibility ofturning about said theoretical axis of the piston 44 during operation.

The head member 48 c is provided with a middle, sleeve-shaped carryingportion 48 g having rib portions 48 g′ projecting laterally outwardswhich form a locking engagement with equivalent cavities (not shownfurther) internally in the associated piston rod 48 (see FIGS. 1a and 1b).

In FIG. 1a the pistons 44,45 are shown in their equivalent, one outerposition. This outer position, where there is a maximum spacing betweenthe pistons 44,45, is designated herein generally as a dead point 0 afor the piston 44 and 0 b for the piston 45.

In the said dead point positions 0 a and 0 b the piston 44 uncovers thescavenging ports 24, while the piston 45 uncovers the exhaust ports 25,opening and closing of the scavenging ports 24 being controlled bypositions of the piston 45 in the associated cylinder 21, while openingand closing of the exhaust ports 25 is controlled by positions of thepiston 44 in the associated cylinder 21. This control will be describedin more detail in what follows having regard to FIGS. 12-14.

In addition this control will be described with additional effectshaving regard to the afore-mentioned regulation of the cam guide device12 b along the drive shaft 11.

When the pistons 44,45 occupy their opposite outer positions, wherethere is a minimal spacing between, as is shown in FIG. 1b, thesepositions are usually designated as dead point positions. Howeveraccording to the present invention the pistons 44,45 are stationary,that is to say without or broadly speaking without axial movementrelative to each other in and at these dead point positions. In that thepistons are held stationary not only in the dead point position, butalso in adjacent portions of the respective “sine”-like plane, as willbe described further below, a volumetrically more or less constantworking chamber (combustion chamber) over a certain arcuate length canbe ensured, that is to say over a considerably longer portion of the“sine”-like plane than known hitherto.

Consequently the pistons 44,45 are at rest or broadly speaking at restover a portion of the “sine”-like plane, which is designated herein as a“dead portion” 4 a for the piston 44 and as a “dead portion” 4 b for thepiston 45. Such dead portions 4 a and 4 b are further illustrated inFIGS. 12 and 13.

In said dead portions there is defined in the working chamber K aso-called “dead space”, which herein (for reasons which will be evidentfrom what follows) is designated as the combustion chamber K1. Thecombustion chamber K1 is according to the invention mainly defined inand at a transition portion between the compression phase and expansionphase of the two cycle engine, as will be described in more detail inwhat follows.

During the expansion phase, that is to say from the position of thepiston as shown in FIG. 1b to the position of the piston as shown inFIG. 1a, the working chamber K is expanded from a minimum volume, shownby the combustion chamber K1, gradually to a maximum volume, as shown inFIG. 1a and at said dead point 0 a and 0 b in FIGS. 9 and 10, thecombustion chamber K1 being gradually expanded with another chamber K2in which the expansion and compression strokes of the pistons 44,45 takeplace.

According to the invention the combustion chamber K1 is defined to aconsiderable degree in said dead portion/dead space. In practice howeverthe combustion can also continue a bit just outside said dead space,something which will be explained in more detail below.

In connection with the change of the compression ratio in the workingchamber there can be a question in the position as shown in FIG. 10about different volumes in the combustion chamber K1 all according towhich regulation is effected during use of the engine. From the abovethere should in that case also be a question about different volumes inthe combustion chamber in the opposite position as shown in FIG. 1a.

However one must be aware of the piston strokes for the individualpiston 44,45 being precisely equally long under all operativeconditions, regardless of the compression ratio which must be employed.

Each piston 44,45 is rigidly connected to its respective pipe-shapedpiston rod 48 and 49, which is guided in a rectilinear movement via aso-called cross-head control 50. The cross-head control 50 is arrangedpartly in the engine block 17 and partly in the respective cover member17 a and 17 b at the equivalent free outer end of the respective pistonrod 48,49. The cross-head control 50, which is shown in detail in FIG.5a, forms an axial guide for the piston rod 48 and 49 just within andjust outside the engine block 17.

With reference to FIG. 5a there is a rotary pin 51 which is fastened atone end of the pipe-shaped piston rod 48 and which passes through thepiston rod 48 crosswise, that is to say through its pipe hollow space52. On a middle portion 51 a of the rotary pin 51, that is to sayinternally in said hollow space 52, there is rotatably mounted a maincastor 53, while on one end portion 51 b of the rotary pin 51 on theoutwardly facing side 48 a of the piston rod 48 there is rotatablymounted an auxiliary castor 55.

The main castor 53 comprises an inner hub portion 53 a having a rollerbearing 53 b and an outer rim portion 53 c. The rim portion 53 c isprovided with a double curved, that is to say ball sector-shaped rollersurface 53 c′.

The auxiliary castor 55 has a construction corresponding to the maincastor 53 and comprises an inner hub portion 55 a, a middle rollerbearing 55 b and an outer rim portion 55 c with ball sector-shapedroller surface 55 c′.

The main castor 53 is adapted to be rolled off along a roller surface 54concavely curved in cross-section, which forms a part of a so-called“sine”-like curve 54′ as shown in FIGS. 6-8. By employing a ballsector-shaped roller surface 53 c′, which rolls along an equivalentlycurved guide surface 54 of the cam guide device 12 a and 12 b, aneffective support abutment can be ensured between the castor 53 and theguide surface 54 under varying working conditions, and possibly with asomewhat obliquely disposed castor and/or obliquely disposed piston rod48 (49), such as this being able to be permitted in the pivotablemounting of the piston rod 48 in the piston 44, as shown in FIG. 5h.

The “sine”-like curve 54′ is designed in the cam guide device 12 a and12 b of the drive shaft on a side facing equivalently axially outwardsfrom the intermediate cylinder's 21. The auxiliary castor 55 is adaptedto be rolled off against and along an equivalent, other “sine”-likecurve (not shown further) concavely curved in cross-section along aroller surface 56 a in a roller path, which is designed in the cam guidedevice 12 a (and 12 b) radially just within the roller surface 54.

In the embodiment illustrated in FIG. 5a the “sine”-like curve 54 a′ isplaced radially outermost, while the “sine”-like curve 56 a′ is placedin the cam guide device 12 a a distance radially within the “sine”-likecurve 54 a′. Alternatively the “sine”-like curve 54 a′ can be arrangedradially within the “sine”-like curve 56 a′ (in a manner not shownfurther).

In each of the cam guide devices 12 a and 12 b there are designed acorresponding pair of “sine”-like curves 54 a′, 56 a′ in a manner notshown further and each “sine”-like curve can be provided with one ormore “sine”-like planes as required.

In FIG. 1 schematic reference is made to a cam guide device 12 a and 12b, while the details in the associated “sine”-like curves and“sine”-like planes are shown further in FIGS. 9-14.

The “sine”-like Concept.

Generally the “sine”-like concept can be applied with an odd numberednumber (1,3,5 etc.) of cylinders, while an even numbered (2,4,6 etc.)number of “sine”-like planes is employed and vice-versa.

In a case where there is employed in each of the cam guide devices 12 aand 12 b a single “sine”-like plane (having a “sine”-like top and a“sine”-like bottom), that is to say the “sine”-like plane covers anangular arc of 360°, it is however immaterial whether an odd numbered oreven numbered number of cylinders is employed. Correspondingly with anumber of two (or more) “sine”-like planes there can for instance beemployed a larger or smaller number of cylinders as required.

The said case with a single “sine”-like plane can be especially ofinterest for use in engines running rapidly which are driven at speedsover 2000 rpm.

According to the “sine”-like concept the individual engine can be“internally” geared with respect to speed, all according to which numberof “sine”-like tops and “sine”-like bottoms is to be employed at each360° revolution of the drive shaft. In other words according to the“sine”-like concept both engines can be built precisely in therevolutions per minute region which is relevant for the individualapplication.

Generally the series arranged cylinders of the engine, with associatedpistons, of the illustrated embodiment are arranged in specific angularpositions around the axis of the drive shaft, for instance with mutuallyequal intermediate spaces along the “sine”-like plane or along theseries of “sine”-like planes (the “sine”-like curve).

For example for a two cycle or four cycle engine numbering threecylinders (see FIG. 6), there can be employed for each 360° revolutiontwo “sine”-like tops and two “sine”-like bottoms and four obliquesurfaces lying between, that is to say two “sine”-like planes arearranged after each other in each cam guide device 12 a,12 b.Consequently in a four cycle motor four cycles can be obtained for eachof the two pistons of the three cylinders with each revolution of thedrive shaft/cam guide devices and four cycles for each of the twopistons of the three cylinders in a two cycle engine.

Correspondingly for a two cycle engine numbering five cylinders, as isshown in FIGS. 9 and 10, there can be employed, for each 360°revolution, a “sine”-like curve with two “sine”-like tops and two“sine”-like bottoms and four oblique surfaces lying between, that is tosay two “sine”-like planes arranged after each other in each cam guidedevice 12 a,12 b, so that in a two cycle engine four cycles are obtainedfor each of the two pistons of the five cylinders with each revolution.

The support rollers of the pistons are placed in the illustratedembodiment with equivalently equal angular intermediate spaces, that isto say in equivalent rotary angular positions along the “sine”-likecurve, so that they are subjected one after the other to equivalentpiston movements in equivalent positions along the respective“sine”-like planes.

The engine power is consequently transferred from the different pistons44,45 one after the other via the support rollers 53 in the axialdirection for the drive shaft 11 via respective “sine”-like curves eachwith their “sine”-like plane, and the drive shaft 11 is therebysubjected to a compulsory rotation about its axis. This occurs by pistonrods of the engine being moved parallel to the longitudinal axis of thedrive shaft and support rollers of the piston rods being forcibly rolledoff along the “sine”-like planes. The engine power is therebytransferred in an axial direction from support rollers of the pistonrods to the “sine”-like planes, which are forcibly rotated together withthe drive shaft 11 about its axis. In other words the transfer of motivepower is obtained from an oscillating piston movement to a rotationalmovement of the drive shaft, the motive power being transferred directlyfrom respective support rollers of the piston rods to “sine”-like planesof the drive shaft.

In FIG. 6a there is schematically illustrated a support roller 53 on anobliquely extending portion of a “sine”-like curve 8 a. Axial drivingforces are shown from an associated piston 44 having piston rod 48 inthe form of an arrow Fa and equivalently in a radial plane decomposedrotational forces transferred to the “sine”-like plane 8 a shown by anarrow Fr.

The rotational forces can be deduced from formula 2:

Fr=Fa.tan f.

According to the invention one achieves inter alia, by means of aparticular design of the “sine”-like plane according to the invention,the expansion stroke of the pistons 44,45—reckoned angularly relative tothe rotational arc of the drive shaft—becoming larger than thecompression stroke of the pistons 44,45. In spite of the differentspeeds of movement of the pistons in opposite directions of movement, arelatively more uniform transfer of motive force to the drive shaft 11can hereby be ensured and in addition a “more uniform”, that is to saymore vibration-free running of the engine.

In FIGS. 6-8 there is schematically shown the mode of operation pf athree cylinder engine 10, in which only the one piston 44 is shown ofthe two co-operating pistons 44,45, illustrated in a planar spreadcondition along an associated “sine”-like curve 54′, which consists oftwo mutually succeeding “sine”-like planes, plus the associated maincastor 53 of the associated one piston rod 48. In each of the FIGS. 6-8there is schematically shown the associated one piston 44 in each ofthree cylinders 21 of the engine, an equivalent arrangement beingemployed for the piston 45 at the opposite end of the cylinders. For thesake of clarity the cylinder 21 and the opposite piston 45 have beenomitted from FIGS. 6-8, only the piston 44, its piston rod 48 and itsmain castor 53 being shown. Axial movements of the piston 44 areillustrated by an arrow 57, which marks the compression stroke of thepiston 44, and an arrow 58, which marks the expansion stroke of thepiston 44.

The “sine”-like curve 54′ is shown with a lower roll path 54, which hasa double “sine”-like plane-shaped contour and which generally guides themovement of the main castor 53 in an axial direction, in that it more orless constantly effects a downwardly directed force from the piston 44via the main castor 53 towards the roll path 54 in the expansion strokeand an upwardly directed force from the roll path 54 via the main castor53 towards the piston 44 in the compression stroke. The auxiliary castor55 (not shown further in FIGS. 6-8) is received with a sure fit relativeto an upper roll path 54 b, as is shown in FIG. 5a. For illustrativereasons the said roll path 56 b is shown vertically above the maincastor 53 in FIGS. 6-8, so as to indicate the maximum movement of themain castor in an axial direction relative to the roll path 54. Inpractice it will be the auxiliary castor 55 which controls thepossibility for movement of the main castor 53 axially relative to itsroll path 54, as is shown in FIG. 5a.

The auxiliary castor 55 is normally not active, but will controlmovement of the piston 44 in an axial direction in the instances themain castor 53 has a tendency to raise itself from the cam-forming rollpath 54. During operation lifting of the main castor 53 in anunintentional manner relative to the roll path 54 can hereby be avoided.The roll path for the auxiliary castor 55 is, as shown in FIG. 5,normally arranged in the fixed fit spacing from the roll path of themain sector 53.

In FIGS. 6-8 the “sine”-like curve 54′ is shown with a first relativelysteep and relatively rectilinear running curve portion 60 and asubsequent, more or less arcuate, top-forming transition portion/deadportion 61 and a second relatively more gently extending, relativelyrectilinearly running curve portion 62 and a subsequent arcuatetransition portion/dead portion 63. These curve contours are however notrepresentative in detail of the curve contours which are employedaccording to the invention, examples of the correct curve contours beingshown in more detail in FIGS. 12 and 13.

The “sine”-like curve 54′ and the “sine”-like plane 54 are shown inFIGS. 6-8 with two tops 61 and two bottoms 63 and two pairs of curveportions 60,62. In FIGS. 6-8 there are illustrated three pistons 44 andtheir respective main castor 53 shown in equivalent positions along anassociated “sine”-like curve in mutually different, succeedingpositions. It is evident from the drawing that the relatively shortfirst curve portions 60 entail that at all times only one main castor 53will be found on the one short curve portion and two or roughly two maincastors 53 on the two longer curve portions 62. In other words with theillustrated curve contour different forms of curve portions can beemployed for the compression stroke relative to the form of the curveportions for the expansion stroke. Inter alia one can hereby ensure thatthe two main castors 53 at all times overlap the expansion stroke, whilethe third main castor 53 forms a part of the compression stroke. Inpractice movement of the piston 44 is achieved with relatively greaterspeeds of movement in the axial direction in the compression stroke thanin the expansion stroke. In themselves these different speeds ofmovement do not have a negative influence on the rotational movement ofthe drive shaft 11. On the contrary it means one is able to observe thatmore uniform and less vibration-inducing movements in the engine can beobtained, with such an unsymmetrical design of the curve portions 60,62relative to each other.

Further there is obtained an increase of the time which is relativelyplaced for disposition in the expansion stroke relative to the timewhich is reserved for the compression stroke.

In a practical construction according to FIGS. 6-8 there is chosen in a180° working sequence an arc length for the expansion stroke of about105° and an equivalent arc length for the compression stroke of about75°. But actual arc lengths can for instance lie between 110° and 95°when the expansion stroke is concerned and equivalently between 700° and85° when the compression stroke is concerned.

On using for instance a set of three cylinders 21 associated with threepairs of pistons 44,45, as is described above, two tops 61 and twobottoms 63 are employed for each 360° revolution of the drive shaft 11,that is to say two expansion strokes per piston pair 44,45 perrevolution.

On using for instance four pairs of pistons there can be correspondinglyemployed three tops and three bottoms, that is to say three expansionstrokes per piston pair per revolution.

In the embodiment according to FIGS. 9-10 there is discussed a fivecylinder engine with five pairs of pistons, associated with two tops andtwo bottoms, that is to say with two expansion strokes per piston pairper revolution.

Typical Cam Guide Arrangement According to the Invention.

In what follows there will be described with reference to FIGS. 9 and 10in more detail a preferred embodiment of the “sine”-like conceptaccording to the invention in connection with a five cylinder, twocycle-combustion engine with two associated, mutually differing camguide curves 8 a and 8 b, as shown in FIGS. 9 and 10 and in FIGS. 12 and13.

In FIG. 14 there is schematically shown a midmost, theoretical cam guidecurve 8 c, which shows the volume change of the working chamber K from aminimum, as shown in the combustion chamber K1 in the dead zones 4 a and4 b, to a maximum, as shown in the maximum working chamber K in the deadpoints 0 a and 0 b (see FIGS. 9-10 and 12-14).

According to the invention the curve 8 b, as is illustrated in FIGS.12-14, is shown at the dead point 0 b phase-displaced an angle ofrotation of 14° in front of the dead point 0 a of the curve 8 a.

The direction of rotation of the curves 8 a and 8 b, that is to say thedirection of rotation of the drive shaft 11, is illustrated by the arrowE.

In FIGS. 9 and 10 there are schematically illustrated five cylinders21-1, 21-2, 21-3, 21-4 and 21-5 and belonging to two associated curves 8a and two curves 8 b, shown spread in a schematically illustratingmanner in one and the same plane. The five cylinders 21-1, 21-2, 21-3,21-4 and 21-5 are shown in respective angular positions with a mutualangular space of 72°, that is to say in positions which are uniformlydistributed around the axis of the rotary shaft 11.

In FIG. 12 there is shown a first curve 8 a, which covers an arc lengthof 180° from a position 0°/360° to a position 180°. A correspondingcurve 8 a (see FIG. 9) passes over a corresponding arc length of 180°from position 180° to position 360°. In other words two succeedingcurves 8 a for each 360° revolution of the drive shaft.

The curve 8 a shows in position 0°/360° a first dead point 0 a. Fromposition 0° to a position 38.4° there is shown a first transitionportion 1 a, which corresponds to a first part of a compression strokeand from position 38.4° to position 59.2° an obliquely (upwardly)extending rectilinear portion 2 a, which corresponds to a main part ofthe compression stroke and from position 59.2° to a position 75° asecond transition portion 3 a, which corresponds to a finishing part ofthe compression stroke.

Thereafter from the position 75° to a position 85° there is shown inconnection with a second dead point a rectilinear dead portion 4 a,which is shown passing over an arc length of 10°.

From the position 80° to a position 95.8° there is shown a transitionportion 5 a, from the position 95.8° to a position 160° an obliquedownwardly extending, rectilinear portion 6 a and from the position 160°to a position 180° a transition portion 7 a. The three portions 5 a,6a,7 a together constitute an expansion portion.

In position 180° is show anew the dead point 0 a and thereafter the camguide curve continues via a second corresponding curve 8 a, from theposition 180° to the position 360°, that is to say with two curves 8 awhich together extend over an arc length of 360°.

In FIG. 13 there is shown an equivalent (mirror image) curve contour forthe remaining curve 8 b, shown with a dead point 0 b and succeedingcurve portion 1 b-7 b.

There is shown the dead point 0 b in a position 346°,

the curve portion 1 b between the positions 346° and 3°,

the curve portion 2 b between the positions 3° and 60°,

the curve portion 3 b between the positions 60° and 75°,

the curve portion 4 b between the positions 75° and 80°,

the curve portion 5 b between the positions 80° and 101.5°,

the curve portion 6 b between the positions 101.5° and 146° and

the curve portion 7 b between the positions 146° and 166°, that is tosay with the dead point 0 b shown anew in the position 166°.

The cam guide continues with a corresponding curve 8 b between thepositions 166° and 346° (see FIG. 10).

The first curve 8 a (FIG. 12) controls opening (position 160°/340°) andclosing (position 205°/25°) of exhaust ports 25.

The second curve 8 b (FIG. 13) control opening (position 146°/326°) andclosing (position 185°/5°) of scavenging ports 24.

In FIG. 14 there is shown a phase-displacement of 14° between the deadpoints 0 a and 0 b, in the illustrated, schematic comparison of thecurves 8 a and 8 b. Curve 8 b, as shown by broken lines in FIG. 14, isfor comparative reasons shown in mirror image form relative to the curve8 a, which for its part is shown in full lines in FIG. 14. By chainlines there is shown the midmost, theoretical curve 8 c, whichillustrates a curve contour approximately like or more like amathematical “sine”-like curve-contour.

In FIGS. 9 and 10 there is shown the “sine”-like plane 8 b in a position14° in front of the position for the “sine”-like plane 8 a. The fivesaid cylinders 21-1, 21-2, 21-3, 21-4 and 21-5 are shown in successivepositions relative to the associated “sine”-like plane and individuallyin successive working positions, as shown in the following diagram 1 anddiagram 2.

Diagram 1 with reference to FIG. 9 and FIG. 12-13. Curve Cyclinder AngleWorking Exhaust Scavenging Zone No. Position Position Ports Ports 8a/8b21-1  3°/183° compression closed open* 1a/1b 21-2  75°/255° compressionclosed closed 4a/4b 21-3  47°/337° expansion closed closed 6a/7b 21-4219°/39° compression closed closed 2a/2b 21-5 291°/101° expansion closedclosed 5b/6a *The scavenging ports 24 open in position 160°/340° andclose in position 25°/205°, that is to say the scavenging ports 24 areheld open over an arc length of 45°.

The exhaust ports 25 are held on the other hand open over an arc lengthof 39°, that is to say over an arc length which is phase-displaced 14°relative to the arc length in which the scavenging ports are open (seeFIG. 14).

The scavenging ports 24 can consequently be open over an arc length of20° (see the curve portions 1 a-3 a in FIG. 12 and the single hatchedsection A′ in FIG. 14) after the exhaust ports 25 are closed. This meansthat the compression chamber over the last-mentioned arc length of 20°can inter alia be supplied an excess of scavenging air, that is to sayis overloaded with compressed air.

Diagram 2 with reference to FIG. 10 and FIG. 12-13. Curve CyclinderAngle Working Exhaust Scavenging Zone No. Position Position Ports Ports8a/8b 21-1  21°/201° compression closed closed 1a/2b 21-2  93°/273°expansion closed closed 5e/5b 21-3 165°/345° expansion open** open*7a/7b 21-4 237°/57° compression closed closed 2a/2b 21-5 309°/129°expansion closed closed 6a/6b **The exhaust ports open in position146°/326° and close in position 185°/5°, that is to say the exhaustports 25 are open over an arc length of 39°.

From FIG. 14 it will be evident from the marked off, individual hatchedsections B′ that the exhaust ports 25 can be held open over an arclength of 14° before the scavenging ports 24 open.

The said sections A′ and B′ show the axial dimensions of the exhaustports 25 and the axial dimensions of the scavenging ports 24 in arespective outer portion of the working chamber K. The ports 24 and 25can thereby be designed of equal height in each end of the workingchamber K. The said height is shown in FIGS. 12-14 by 12.

In an angle zone of 5° (from position 75° to position 80°—see especiallyFIG. 13) of the “sine”-like plane 8 b and in an angle zone of 10° (fromposition 75° to position 85°—see especially FIG. 12) of curve 8 a, therespective associated piston 44 and 45 is held pushed in to the maximumwith a minimum spacing 1 of for instance 15 mm between the piston head44 a and the middle line of the working chamber.

With reference to FIG. 12 it must further be observed that over an arclength of 36.6°, from position 59.2° to position 95.8°, the spacingbetween the piston heads is changed relatively little. The spacing fromthe piston head 44 a to the middle line 44′ is changed from a minimum1=15 mm (in the dead portion 75°-80°) to a 20 mm spacing (position 93°FIG. 13).

Correspondingly the spacing from the piston head to the middle line 44′is changed from a minimum 1=15 mm in the dead portion 75°-80° to a 25 mmspacing in position 57° FIG. 13.

Over said arc length of 36.6° the volume in the combustion chamber K1 iskept approximately constant between the pistons 44,45.

Combined Effects of two Phase-displaced “sine”-like Planes.

From FIG. 14 the contours of the respective two curves 8 a,8 b, whichare shown schematically in mirror image relative to each other will beevident. Curve 8 a is shown real with a full line, while curve 8 b isshown with a broken line, in mirror image about a middle axis betweenthe pistons 44,45. The curve 8 c shows a theoretical midmost curvebetween the curves 8 a,8 b. It will be evident that the midmost curve 8c has a contour which lies more closely up to a sine curve contour thanthe contours of the curves 8 a,8 b individually. Consequently, even ifone gets a relatively unsymmetrical contour in the curves 8 a,8 bmutually, a relatively symmetrical contour of the midmost curve 8 c canbe achieved.

Fuel is Injected:

At the close of the compression phase in curve zone 3 a and 3 b the fuelis injected in a jet with a flow into the rotating scavenging aircurrent and is mixed/atomized effectively in the rotating scavenging aircurrent.

Ignition Starter:

Immediately after the injection of fuel that is to say at the close ofthe compression phase electronically controlled ignition is initiated incurve zone 3 a and 3 b. Provision being made for effective rotation ofthe gas mixture of scavenging air and fuel in a fuel cloud past theignition arrangement. According to the present invention one can aimwith advantage at an ignition delay of 7-10% relative to theconventional ignition angle.

Combustion Phase

In the illustrated embodiment the combustion starts immediately afterignition and is accomplished mainly over a limited region in which thepistons roughly occupy a maximum pushed in position, that is to say atthe close of the curve zone 3 a,3 b, that is to say in a region wherethe pistons are subjected to minimal axial movement. The combustionproceeds mainly or to a significant extent where the pistons 44,45 areheld at rest in the inner dead portion 4 a and 4 b, that is to say overan arc length of 10° and 5° respectively. However the combustioncontinues as required to a greater or smaller degree in the followingtransition portion 5 a,5 b and in the main expansion portion 6 a,6 b,depending upon the speed of rotation of the rotary shaft. As aconsequence of the rotating fuel cloud in the combustion chamber K1 inthe dead portion 4 a,4 b and in that one can keep the flame frontrelatively short in the disc-shaped combustion chamber K1, there can beensured in all instances fuel ignition for a main bulk of the fuel cloudin the combustion chamber K1, that is to say within said dead portion 4a,4 b. In practice the combustion chamber can be allowed to be expandedto the portion 5 a,5 b just outside the dead portion 4 a,4 b withlargely corresponding advantages in a defined volume of the workingchamber K.

Speed of Combustion.

The speed of combustion is as known of an order of magnitude of 20-25meters per second. By the application of a double set of fuel nozzlesand a corresponding double set of ignition arrangements distributed overeach quarter of the peripheral angle of the working chamber (see FIG.4b) the combustion area can be effectively covered over the whole of thedisc-shaped combustion chamber K1. In practice especially favorablecombustion can thereby be achieved with relatively short flame lengths.

Optimal Combustion Temperature:

As a result of the concentrated ignition/combustion zone 3 a,3 b whichis defined in the chamber K just in front of the combustion chamber K1and the region 5 a,5 b immediately after the combustion chamber K1, thatis to say in a coherent region 3 a-5 a and 3 b-5 b, where the pistons44,45 are at rest or largely at rest, it is possible to increase thecombustion temperature from usually about 1800° C. to 3000° C. It ispossible thereby to achieve an optimal (almost 100%) combustion of thefuel cloud even before the pistons 44,45 have commenced fully theexpansion stroke, that is to say at the end of the curve portions 5 a,5b.

Ceramic Ring.

Provision is made for a ceramic ring, that is to say a ceramic coatingapplied in an annular zone of the working chamber K corresponding to acombustion region (3 a-5 a,3 b,5 b), so that high temperatures can beemployed especially in the combustion chamber K1, but also in thefollowing portion 5 a,5 b of the combustion region. The ceramic ringwhich is shown with a dimension as indicated by a broken line 70 inFIGS. 12-14, comprises the whole combustion chamber K1 and is inaddition extended further outwards in the combustion chamber over adistance 13.

Introductory Expansion Stroke.

After at least considerable portions of the fuel are consumed in theafore-mentioned combustion region (3 a-5 a, 3 b,5 b) and one has juststarted the expansion stroke there are generally optimal motive forces.More specifically this means that by way of the cam guide along thecurves 8 a and 8 b there is obtained an optimal driving momentimmediately the expansion stroke commences in the transition region 5a,5 b and increases towards a maximum in the transition region 5 a,5 b.The driving moment is maintained largely constant in the continuation ofthe expansion stroke (in the region 6 a,6 b) and at least in thebeginning of this region, as a consequence of possible after burn offuel in this region in spite of the volumetric expansion which occursgradually in the chamber K as the expansion stroke proceeds forwardthrough this.

Expansion Phase.

According to the illustrated embodiment the compression phase takesplace relative to the curves 8 a,8 b under angles of inclination ofbetween about 25° and about 36° in the respective two curves 8 a and 8b, that is to say with a mean angle (see FIG. 14) of about 30°. Ifdesired the angles of inclination (and the mean angle) can for instancebe increased to about 45° or more as required. The expansion phase takesplace correspondingly in the illustrated embodiment at between about 22°and 27° in the two curves 8 a and 8 b, that is to say while at a meanangle (see FIG. 14) of about 24°.

As a result of the relatively steep (mean) curve contour of 30° in thecompression phase and the relatively gentler contour 24° in theexpansion phase, there is achieved a particularly favorable increase ofthe durability in time of the expansion stroke relative to thedurability of the compression stroke.

According to the invention one can by means of said unsymmetricalrelationship between the speed of movement in the compression stroke andthe speed of movement in the expansion stroke, displace the start of thecombustion process in the compression phase closer up to the inner deadpoint and thereby time-displace a larger part of the combustion processto the beginning of the expansion phase, without this having negativeconsequences for the combustion. Consequently there can be achieved abetter control and a more effective utilisation of the motive force ofthe fuel combustion in the expansion phase than hitherto. Inter aliathere can be displaced an otherwise possibly occurring, uncontrolledcombustion from the compression phase over the dead point to theexpansion phase and thereby convert such “pressure points”, whichinvolve uncontrolled combustion in the compression phase, to useful workin the expansion phase.

By extending the expansion phase at the expense of the compression phasea relatively higher piston movement is obtained in the compression phasethan in the expansion phase. This has an influence on each set ofpistons of the combustion engine in every single working cycle.

Rotation Effect in the Working Chamber.

There is established rotation of the gases in the working chamber byejecting exhaust gases via obliquely disposed exhaust ports 25 (see FIG.2) followed by the injection of scavenging air via the obliquelydisposed scavenging air ports 24 (see FIG. 3). There is set up thereby arotating, that is to say helical gas flow path (see arrow 38 in cylinder21-1 in FIG. 9) which is maintained over the whole working cycle. Therotational effect is reactivated in the course of the working cycle,that is to say during the injection, ignition and combustion phases.

There is consequently supplied a new rotational effect to the gas flow38 during transit in the working cycle by fuel injection via the nozzle36 and subsequent fuel ignition via the ignition arrangement 39, theattendant combustion producing a direction fixed flame front with anassociated pressure wave front roughly coinciding with the gas flow 38already established. The rotational effect is consequently maintainedduring the whole compression stroke and is reactivated during transit byinjecting fuel via an obliquely disposed nozzle jet 37, as shown in FIG.4a, via a corresponding obliquely disposed nozzle mouth 36. Additionalrotational effects are obtained in the combustion phase.

A still additional increase of the rotational effect can be obtainedaccording to the construction as shown in FIG. 4b by the application ofan extra (second) fuel nozzle 37 a, which is disposed angularlydisplaced relative to the first fuel nozzle 37, and by the applicationof an extra ignition arrangement 39 a, which is disposed angularlydisplaced relative to the first ignition arrangement 39. When theexhaust ports 25 open again, on the termination of the working cycle,the exhaust gas is exhausted with a high speed of movement, that is tosay with a high rotational speed, during exhaustion of exhaust gas viathe said obliquely disposed exhaust ports. Further the rotational effectfor the exhaust gases is maintained immediately the obliquely disposedscavenging ports 24 open, so that the residues of the exhaust gases arescavenged with a rotational effect outwardly from he working chamber Kat the close of the expansion phase and the beginning of the compressionphase. Thereafter the rotational effect is maintained, after closing ofthe exhaust ports, the scavenging ports being continued to be held openover a significant arc length.

Regulation of the Compression Ratio of the Engine During Operation.

According to the invention it is possible to regulate the volume betweenpistons 44,45 of the cylinder 21 by regulating the mutual spacingbetween the pistons 44,45. It is hereby possible to directly regulatethe compression ratio in the cylinder 21 as required, for instanceduring operation of the engine by means of a simple regulation techniqueadapted according to the “sine”-like concept.

It is especially interesting according to the invention to change thecompression ratio in connection with starting up the engine, that is tosay on cold start, relative to a most favorable compression ratiopossible during usual operation. But it can also be of interest tochange the compression ratio during operation for various other reasons.

A constructional solution for such a regulation according to theinvention is based on pressure oil-controlled regulating technique.Alternatively there can be employed for instance electron-controlledregulating technique, which is not shown further herein, for regulatingthe compression ratio.

Alternatively there can be employed a corresponding regulatingpossibility also for the piston 45 by replacing the cam guide device 12a with a cam guide device correspondingly as shown for the cam guidedevice 12 b.

It is apparent according to the invention that it is possible toregulate the position of both pistons 44,45 in the associated cylindervia their respective cam guide arrangement with their respectiveseparate possibility of regulation, in a mutually independent manner.

It is also apparent that the regulation of the position of the pistonsin the cylinder can be effected synchronously for the two pistons 44,45or individually as required.

In FIGS. 15 and 16 there is shown schematically an alternative solutionof certain details in a cam guide device, as it is referred to herein bythe reference numeral 112 a, and of an associated piston rod, as shownby the reference numeral 148 as well as a pair of pressure rollers, asshown by the reference numerals 153 and 155.

The Cam Guide Device 112 a:

In the construction according to FIG. 1 the cam guide device 12 a isshown having a relatively space-demanding design with associated casters53 and 55 arranged at the side of each other in the radial direction ofthe cam guide device 12 a, that is to say with the one caster 53arranged radially outside the remaining caster 55 and with theassociated “sine”-like grooves 54,55 c illustrated correspondinglyradially separated on each of their radial projections.

In the alternative construction according to FIGS. 15 and 16 the camguide device 112 a is shown with associated pressure spheres 153, 155arranged in succession in the axial direction of the cam guide device112 a, that is to say with a sphere on each respective side of anindividual, common projection, illustrated in the form of anintermediate annular flange 112. The annular flange 112 is shown with anupper “sine”-like curve forming “sine”-like groove 154 for guiding anupper pressure sphere 153, which forms the main support sphere of thepiston rod 148, and a lower “sine”-like curve forming “sine”-like groove155 a for guiding a lower pressure sphere 155, which forms the auxiliarysupport sphere of the piston rod 148. The grooves 154 and 155 a have, asshown in FIG. 15, a laterally concavely rounded form corresponding tothe spherical contour of the spheres 153,155. The annular flange 112 isshown having a relatively low thickness, but the low thickness can becompensated for as to strength in that the annular flange 112 has in theperipheral direction a self-reinforcing “sine”-like curve contour, suchas indicated by the obliquely extending section of the annular flangeillustrated in FIG. 16. In FIG. 15 the annular flange 112 is shownsegmentally in section, while in FIG. 16 there is shown in cross-sectiona peripherally locally defined segment of the annular flange 112, seenfrom the inner side of the annular flange 112.

There can be employed a largely corresponding design of theafore-mentioned details in both cam guide devices, that is to say alsoin the cam guide device not shown further corresponding to the lower camguide device according to FIG. 1.

The Piston Rod 148:

According to FIG. 1 a pipe-shaped, relatively voluminous piston rod 48is shown, while in the alternative embodiment according to FIGS. 15 and16 there is illustrated a slimmer, compact, rod-shaped piston rod 148having a C-shaped head portion 148 a with two mutually opposite sphereholders 148 b,148 c for a respective pressure sphere 153,155.

The piston rod 148 can in a manner not shown further be provided withexternal screw threads which cooperate with internal screw threads inthe head portion, so that the piston rod and thereby the associatedsphere holder 148 b can be adjusted into desired axial positionsrelative to the head portion 148 a. This can inter alia facilitate themounting of the sphere holder 148 b and its associated sphere 153relative to the annular flange 112.

In FIG. 16 the annular flange 112 is shown with a minimum thickness atobliquely extending portions of the annular flange, while the annularflange 112 can have in a manner not shown further a greater thickness atthe peaks and valleys of the “sine”-like curve, so that a uniform orlargely uniform distance can be ensured between the spheres 153,154along the whole periphery of the annular flange.

By the reference numeral 100 there is referred to herein a lubricatingoil intake, which internally in the C-shaped head portion 148 a branchesoff into a first duct 101 to a lubricating oil outlet 102 in the uppersphere holder 148 b and into a second duct 103 to a lubricating oiloutlet 104 in the lower sphere holder 148 c.

The Pressure Spheres 153,155:

Instead of the casters 53,55 shown according to FIG. 1, which aremounted in ball bearings, pressure spheres 153,155 are shown accordingto FIGS. 15 and 16. The pressure spheres 153,155 are mainly adapted tobe rolled relatively rectilinearly along the associated “sine”-likegrooves 154,155 a, but can in addition be permitted to be rolledsideways to a certain degree in the respective groove as required. Thespheres 153 and 155 are designed identically, so that the sphere holders148 a,148 b and their associated sphere beds can also be designedmutually identically and so that the “sine”-like curves 154,155 a canalso be designed mutually identically.

The pressure spheres 153,155 are shown hollow and shell-shaped with arelatively low wall thickness. There are obtained hereby pressurespheres of low weight and small volume, and in addition there isachieved a certain elasticity in the sphere for locally relievingextreme pressure forces which arise in the sphere per se.

In FIGS. 17 and 18 a pair of guide rods 105,106 are shown which passthrough internal guide grooves 107,108 along opposite sides of the headportion 148 a of the piston rod 148.

What is claimed is:
 1. Arrangement of a two cycle combustion engine(10,100) having internal combustion, comprising a number of enginecylinders (21; 21-1-21-5), which are arranged in an annular seriesaround a common middle drive shaft (11) and which have cylinder axesrunning parallel to the drive shaft, each cylinder including a pair ofpistons (44,45) movable towards and away from each other and a common,intermediate working chamber (K) for each pair of pistons, while eachpiston (44,45) is provided with its axially movable piston rod (48,49),the free outer end of which forms via a support roller (53,55) a supportagainst its curve-shaped, “sine”-like curve shaped, cam guide device (12a,12 b), which is arranged at each of opposite ends of the cylinder (21;21-1-21-5) and which controls movements of the piston relative to theassociated cylinder, characterized in that the two pistons (44,45) ineach cylinder (21; 21-1-21-5) have mutually differing piston phases,which are controlled by mutually differing cam guide devices (12 a,12b), the cam guide devices (12 a,12 b) being designed with equivalentmutually differing “sine”-like planes (8 a,8 b), the respective camguide devices (12 a, 12 b) of the two pistons (44,45), in certainportions (1 a-3 a, 5 a-7 a; 1 b-3 b, 5 b-7 b) of the “sine”-like plane(8 a,8 b) are phase-displaced relative to each other and that remainingportions (4 a,4 b) of the “sine”-like planes are in mutual phase.
 2. Incombination a rotatable drive shaft; an engine block having a pluralityof cylinders disposed in parallel relation about a common central axis;a pair of pistons disposed in facing relation to each other in at leastone of said cylinders to define a working chamber therebetween, eachsaid piston being reciprocally mounted in said one cylinder; a pair ofpiston rods, each piston rod being connected to a respective one of saidpistons for movement therewith and extending outwardly of said engineblock; a drive shaft disposed on said central axis and extending throughsaid engine block; and a pair of cam guide devices connected to oppositeends of said drive shaft, each cam guide device having a curved camsurface in contact with a respective one of said piston rods forrotation of said cam guide device in response to an axial movement ofsaid one piston rod and for rotating said drive shaft therewith, saidcurved cam surface of one of said cam guide devices having portionsthereof in phase-displaced relation to portions of said curved camsurface of the other of said cam guide devices and portions thereof inmutually-phased relation to portions of said curved cam surface of saidother of said cam guide devices.
 3. The combination as set forth inclaim 2 which further comprises a support roller on one end of arespective piston rod and in rolling contact with said cam surface of arespective cam guide device.
 4. The combination as set forth in claim 2wherein each said cam surface is a sine-like curved cam surface.
 5. Thecombination as set forth in claim 2 said cam surface of at least one ofsaid cam guide devices includes a rectilinear portion corresponding to astationary “dead point” position of a respective one of said pistons insaid cylinder between a compression stroke and an expansion stroke ofsaid one piston in said cylinder.
 6. The combination as set forth inclaim 5 wherein stationary “dead point” position of said one pistondefines, in part, a combustion chamber within said working chamber forcombustion of a major fuel portion immediately before said expansionstroke.
 7. The combination as set forth in claim 6 wherein eachstationary “dead point” position occurs over an arc length of from 5° to10° of the rotational arc of said drive shaft.
 8. The combination as setforth in claim 2 wherein said one cylinder has a plurality of scavengingports for delivering combustion air into said working chamber and aplurality of exhaust ports for expelling combusted gases from saidworking chamber, one of said pistons being disposed to open and closesaid scavenging ports and the other of said pistons being disposed toopen and close said exhaust ports during reciprocation thereof.
 9. Thecombination as set forth in claim 8 wherein said curved cam surface ofone of said cam guide devices has a portion phase-displaced from saidcurved cam surface of the other of said cam guide devices to effectopening of said exhaust ports prior to opening of said scavenging ports.10. The combination as set forth in claim 2 wherein said cam surface ofeach of said cam guide devices includes a rectilinear portioncorresponding to a stationary “dead point” position of a respective oneof said pistons in said cylinder between a compression stroke and anexpansion stroke of said one piston in said cylinder.
 11. Thecombination as set forth in claim 10 wherein said stationary “deadpoint” position of each said piston defines, in part, a combustionchamber within said working chamber of said respective piston forcombustion of a major fuel portion immediately before said expansionstroke.
 12. The combination as set forth in claim 10 wherein each saidcylinder has a plurality of scavenging ports for delivering combustionair into a respective working chamber and a plurality of exhaust portsfor expelling combusted gases from said respective working chamber, oneof said pistons in each said cylinder being disposed to open and closesaid scavenging ports and the other of said pistons in each saidcylinder being disposed to open and close said exhaust ports duringreciprocation thereof.
 13. The combination as set forth in claim 12wherein said curved cam surface of one of said cam guide devices of arespective cylinder has a portion phase-displaced from said curved camsurface of the other of said cam guide devices of said respectivecylinder to effect opening of said exhaust ports prior to opening ofsaid scavenging ports.